Variation of Species

Abstract

ON p. 181 of Wallace's “Darwinism,” ed. 1889, this passage occurs:—“Let us suppose that a given species consists of 100,000 individuals of each sex, with only the usual amount of fluctuating external variability. Let a physiological variation arise, so that 10 per cent. of the whole number—10,000 individuals of each sex—while remaining fertile inter se become quite sterile with the remaining 90,000. This peculiarity is not correlated with any external differences of form or colour, or with inherent peculiarities of likes or dislikes leading to any choice as to the pairing of the two sets of individuals. We have now to inquire, What would be the result?”